Monitoring or tracking eye movements and detecting a person's gaze point (as used herein, the point in space at which the person is looking) can be used in many different contexts. Such measurements can be an important information source in analysing the behaviour and consciousness of the person. The information can be used both for evaluating a test scene (as used herein, the visual percept of a region of space in which visible objects or surfaces may be present and inside which a gaze point can be detected) observed by a person, and for evaluating characteristics of the respective person. The diverse uses of gaze point detection include studies on the usability of software and different types of interfaces; evaluation of web pages, advertising and advertisements; provision of means for educating pilots in simulator environments and for training surveillance personnel in security-critical roles; and research in psychology, behavioural sciences and human perception. A field which has attracted an increasing interest in recent years is the evaluation of advertising and other marketing channels. Eye-tracking information may then be gathered from a viewing test person's examination of advertising of a particular merchandise, and the response of the test person is derived. Eye-tracking devices may also be used for collecting information on the response of the viewing person of the placement of a particular article on a shelf of a shop display.
In addition to these applications, there are interactive applications which employ information about the area at which a person is looking in order to respond or react in different ways. For example, the advertising or display of goods in a shop window can undergo a visual change responsive to the detected fact that a person is looking at it. Moreover, a computer system may utilise continuous information on the gaze point of a user to be better capable of displaying the object in which a user is interested and of adapting it intelligently to different behaviours of the user. Thus, an eye-tracker could form part of an interface for human-computer interaction. Since the content of the display is programmed in software, software can also correlate gaze-point information with the semantics of the program.
While eye-tracking-assisted studies of human behaviour up to now have been concerned with a limited number of individuals, many market researchers wish to carry eye-tracking technology over to the statistical, high-volume approach which has historically been very successful in this field. For instance, the cumulated reactions to a particular advertisement campaign of a large number of test subjects may provide an accurate prediction of the efficiency of this campaign during its future, full-scale exposure in society. This emerging use of eye trackers leads to new challenges on the technological level. For instance, available eye trackers are usually complex and fragile devices, and their operation may be demanding—at least to a user having a background in areas such as marketing studies or behavioural sciences rather than a relevant technological field. The applicability of eye-tracking technology to high-volume studies is limited by two facts in particular. Firstly, adapting an eye tracker to a new person may be a time-consuming and technologically demanding exercise, and secondly, many potential test subjects may feel hesitant or reluctant to using such a device if its interface is complicated or physically intrusive.
As seen above, for an equipment to be suitable for gaze-point detection in group studies, it is important that it can switch between the test subjects quickly and conveniently. On a different level, the eye-tracking equipment should also be easily deployable in different environments, and the visual objects to which the test subjects are to be exposed should not be limited to, e.g., computer monitors. Indeed, from the point of view of marketing research, eye-tracking-based studies may be of interest in any environment where consumers receive visual information on which to base their buying decisions, and the range of possible psychological experiments to which eye-tracking technology is applicable seems unlimited.
In conclusion, there appears to be a need for an eye-tracking system which solves at least some of the problems discussed above.